Synergistic interplays between the selective electron-phonon coupling, antiferromagnetic fluctuations and charge density wave in the YBa2Cu3Ox cuprate superconductor

Abstract: This research aims to investigate the synergistic effect between charge density wave, selective electron-phonon coupling under antiferromagnetic fluctuations, as well as the unusual electron distribution observed in ARPES data in YBa2Cu3Ox superconductors (YBCO). By considering their synergistic impact, our model can calculate the superconducting transition temperature Tc of YBa2Cu3Ox as a function of pressure for x = 6.5 and 7 at a reasonable level. Moreover, we have identified a specific antiferromagnetic phonon that contributes significantly to the high Tc observed in YBCO. This finding highlights the significance of these effects in achieving high Tc values. Our study not only identifies an imbalanced charge-density wave effect for triggering selective electron-phonon coupling but also explains why the charge density wave usually occurs around the magnetic copper atoms. Furthermore, our research reveals limitations in the conventional mean-field ab-initio approximation used for antiferromagnetic fluctuations in YBCO. It shows that the dynamic behavior of electrons in YBCO might not be accurately captured by this approximation, as non-uniform magnetic fields under antiferromagnetic fluctuations induce an additional electric potential on electrons across the boundary between non-magnetic to magnetic sites instantaneously. This instantaneous electric potential, in turn, suggest that the influence of the antiferromagnetic phonon-based pairing mechanism might not have been optimized in theory